tree: Replace ShiftLeft(a,b) with ASL 2.0 syntax

Replace `ShiftLeft (a, b)` with `a << b`.

Change-Id: I812b1ed9dcf3a5749b39a9beb9f870258ad6a0de
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70842
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/intel/skylake/acpi/xhci.asl b/src/soc/intel/skylake/acpi/xhci.asl
index da5c10b..31d2152 100644
--- a/src/soc/intel/skylake/acpi/xhci.asl
+++ b/src/soc/intel/skylake/acpi/xhci.asl
@@ -17,7 +17,7 @@
 	Local0 = Arg1 + ((Arg0 - 1) * 0x10)
 
 	/* Map ((XMEM << 16) + Local0 in PSCR */
-	OperationRegion (PSCR, SystemMemory, ShiftLeft (Arg2, 16) + Local0, 0x10)
+	OperationRegion (PSCR, SystemMemory, (Arg2 << 16) + Local0, 0x10)
 	Field (PSCR, DWordAcc, NoLock, Preserve)
 	{
 		PSCT, 32,
@@ -100,7 +100,7 @@
 		D3HE, 1,	/* D3_hot_en */
 	}
 
-	OperationRegion (XREG, SystemMemory, ShiftLeft (XMEM, 16) + 0x8000, 0x200)
+	OperationRegion (XREG, SystemMemory, (XMEM << 16) + 0x8000, 0x200)
 	Field (XREG, DWordAcc, Lock, Preserve)
 	{
 		Offset (0x1c4),	/* USB2PMCTRL */